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Skeletal muscle relaxants Pharmacokinetics Indications Chlorzoxazone synthesis Medicine interactions Side effects Uses Category Toxicity grading Acute toxicity Flammability and hazard properties Storage characteristics Extinguishing agent
Chemical Name:
Molecular Formula:
Formula Weight:
MOL File:

Chlorzoxazone Properties

Melting point:
191-192 °C(lit.)
1.3771 (rough estimate)
refractive index 
1.5557 (estimate)
storage temp. 
-20°C Freezer
DMSO: soluble50mg/mL, clear
pKa 8.3 (Uncertain)
white to off-white
Water Solubility 
0.1 g/100 mL
CAS DataBase Reference
95-25-0(CAS DataBase Reference)
NIST Chemistry Reference
EPA Substance Registry System
2(3H)-Benzoxazolone, 5-chloro-(95-25-0)
  • Risk and Safety Statements
  • Hazard and Precautionary Statements (GHS)
Hazard Codes  Xn,T,Xi
Risk Statements  22-36/37/38-20/21/22
Safety Statements  26-36-24/25-37/39
WGK Germany  3
RTECS  DM5250000
Hazard Note  Toxic/Irritant
HazardClass  IRRITANT
HS Code  29349990
Toxicity LD50 in mice (mg/kg): 3650 orally, 380 i.p. (suspensions); 440 orally, 183 i.p. (solns of Na salt) (Hofrichter)
Signal word: Warning
Hazard statements:
Code Hazard statements Hazard class Category Signal word Pictogram P-Codes
H301 Toxic if swalloed Acute toxicity,oral Category 3 Danger P264, P270, P301+P310, P321, P330,P405, P501
H302 Harmful if swallowed Acute toxicity,oral Category 4 Warning P264, P270, P301+P312, P330, P501
H315 Causes skin irritation Skin corrosion/irritation Category 2 Warning P264, P280, P302+P352, P321,P332+P313, P362
H319 Causes serious eye irritation Serious eye damage/eye irritation Category 2A Warning P264, P280, P305+P351+P338,P337+P313P
H335 May cause respiratory irritation Specific target organ toxicity, single exposure;Respiratory tract irritation Category 3 Warning
Precautionary statements:
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P264 Wash hands thoroughly after handling.
P264 Wash skin thouroughly after handling.
P270 Do not eat, drink or smoke when using this product.
P280 Wear protective gloves/protective clothing/eye protection/face protection.
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.
P405 Store locked up.
P501 Dispose of contents/container to..…

Chlorzoxazone price More Price(15)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich C4397 Chlorzoxazone 95-25-0 25g $72.1 2018-11-13 Buy
Sigma-Aldrich 1130505 Chlorzoxazone United States Pharmacopeia (USP) Reference Standard 95-25-0 350mg $348 2018-11-13 Buy
TCI Chemical C2237 Chlorzoxazone >98.0%(GC)(T) 95-25-0 25g $40 2018-11-22 Buy
TCI Chemical C2237 Chlorzoxazone >98.0%(GC)(T) 95-25-0 250g $209 2018-11-22 Buy
Alfa Aesar B24507 5-Chloro-2(3H)-benzoxazolone, 99% 95-25-0 50g $50.7 2018-11-15 Buy

Chlorzoxazone Chemical Properties,Uses,Production

Skeletal muscle relaxants

Chlorzoxazone is an orally active central skeletal muscle relaxant with its chemical structure being completely different with all the other muscle relaxants. It, mainly through acting on the central cerebral cortex and the spinal cord, inhibits the multi-synaptic reflection related to muscle spasms and produces muscle relaxation, further relieves the spasm caused pain and increase the flexibility of the muscles involved. Acetaminophen belongs to non-steroidal anti-inflammatory drugs and may mainly exert the analgesic and antipyretic effects through the inhibition of prostaglandin synthesis. Muscle relaxation studies through mouse traction test have demonstrated that the compound Chlorzoxazone showed a dose-dependent muscle relaxant effect with excellent protective effect on the strychnine-induced seizures in mice. The existence of paracetamol in the compound chlorzoxazone tablets can further enhance the effect of chlorzoxazone. Hot plate analgesic tests have showed the compound chlorzoxazone has a significant analgesic effect in a dose-dependent manner. It also has antagonism effect on the painful writhing of mice caused by antimony potassium tartrate in a good dose-response relationship. Test results have showed that acetaminophen and chlorzoxazone analgesic synergy.
This information is edited by Xiongfeng Dai from Chemicalbook.


This product can be completely absorbed by the digestive tract with the plasma concentration reaching peak at 1.5-2 hours. It is distributed in muscle, kidney, liver, brain and fat. After 6 hours, the drug concentration decreases significantly. Almost all of the goods can subject to in vivo catabolism with the elimination half-life being about 1 hour.
This information is edited by Xiongfeng Dai from Chemicalbook.


Chlorzoxazone is suitable for the treatment of various kinds of acute and chronic soft tissue (muscles, ligaments and fascia) sprain, contusion, muscle pain after exercise, pain caused by muscle strain and the muscle spasms caused by the central nervous system lesions as well as chronic fasciitis.

Chlorzoxazone synthesis

Take 2, 5-dichloro-nitrobenzene as raw material; go through hydrolysis, reduction reaction to give 2-amino-4-chloro-phenol, followed by cyclization reaction in hydrochloric acid to obtain the finished product of Chlorzoxazone with the total yield being 84%.

Medicine interactions

When this product is used in combination with central inhibitory drugs such as phenothiazines and barbituric acid derivative and monoamine oxidase inhibition drugs, we should reduce the usage amount of this product.

Side effects

There may be occasionally mild drowsiness, dizziness, nausea, heart palpitations, weakness, abdominal pain and other reactions. This drug should be discontinued in case of allergic reactions. These adverse reactions are generally mild and may go away automatically or alleviated after stopping using this drug.


It can be used as pharmaceutical intermediates.
It can be used as central muscle relaxants, for being applied to a variety of soft tissue pain caused by chronic sprain, contusion and muscle strain as well as muscle spasms and pain caused by the central nervous system and so on.


Toxic substances.

Toxicity grading

Highly toxic.

Acute toxicity

Oral-rat LD50: 763 mg/kg; Oral-Mouse LD50: 440 mg/kg.

Flammability and hazard properties

Thermal decomposition can release nitrogen oxides and chlorides smoke.

Storage characteristics

Treasury: ventilated, low temperature and dry; store it separately from food raw materials.

Extinguishing agent

Water, carbon dioxide, foam, powder.

Chemical Properties

White to Off-White Solid


Muscle relaxant (skeletal)


For the relief of discomfort associated with acute painful musculoskeletal conditions.


ChEBI: A member of the class of 1,3-benzoxazoles that is 1,3-benzoxazol-2-ol in which the hydrogen atom at position 5 is substituted by chlorine. A centrally acting muscle relaxant with sedative properties, it is used for the symptomatic treatment of painful mus le spasm.


Chlorzoxazone is a benzoxazolone derivative that causes skeletal muscle relaxation and blocks spasticity in clinical studies. Chlorzoxazone enhances small and intermediate conductance calcium-activated potassium channels (EC50s = 87 and 98 μM for KCa2.2 and KCa3.1, respectively). The cytochrome P450 isoform CYP2E1 converts chlorzoxazone to 6-hydroxy chlorzoxazone . The urinary excretion of this 6-hydroxy metabolite is often used as a probe of CYP2E1 activity in studies of hepatotoxicity.

brand name

Paraflex (Ortho-McNeil).

Chlorzoxazone Preparation Products And Raw materials

Raw materials

Preparation Products

Chlorzoxazone Suppliers

Global( 205)Suppliers
Supplier Tel Fax Email Country ProdList Advantage
Shenzhen Sendi Biotechnology Co.Ltd.
0755-23311925 18102838259
0755-23311925 CHINA 3217 55
Henan DaKen Chemical CO.,LTD.
+86-371-55531817 CHINA 22058 58
Henan Tianfu Chemical Co.,Ltd.
0371-55170693 CHINA 20795 55
Mainchem Co., Ltd.
+86-0592-6210733 CHINA 32763 55
020-81716319 CHINA 2549 55
+86-571-8723 8903
+86-571-87063838 CHINA 664 58
Jinan Tenglong Chemical Co.,Ltd
Whatsapp:+8615563263311 Skype:live:smions7080 CHINA 778 58
career henan chemical co
+86-371-86658258 CHINA 20000 58
Shanghai Zheyan Biotech Co., Ltd.
18017610038 CHINA 3624 58
J & K SCIENTIFIC LTD. 400-666-7788 +86-10-82848833
+86-10-82849933; China 96815 76

View Lastest Price from Chlorzoxazone manufacturers

Image Release date Product Price Min. Order Purity Supply Ability Manufacturer
2018-12-17 Chlorzoxazone
US $1.00-2.00 / kg 1 kg 99% Customized career henan chemical co

Chlorzoxazone Spectrum

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